Perhaps you’ve been wondering. Does a dehumidifier cool a room? The short answer is *technically* no, it doesn’t, but the full answer is a little more complicated because a dehumidifier does make a room feel cooler even without a lower temperature.
Like most other electrical appliances, a dehumidifier actually increases the ambient temperature by a few degrees. However, a dehumidifier still makes the room feel cooler. This cooling feeling has nothing to do with the changes in temperature. It only feels cooler because of the changes in relative humidity.
How does a dehumidifier do this? Do you really need a dehumidifier? Will it help to run a dehumidifier with an air conditioner? We aim to answer all your questions about the effects and benefits of using a dehumidifier to control room conditions.
How does humidity affect temperature?
Humidity is the amount of water vapor in the air. Relative humidity refers to the amount of water in the air compared to the maximum amount it could hold at a given temperature. It is often a product of the climate and does not affect temperature at all. Humidity only changes our perception of temperature.
Conversely, temperature actually impacts the relative humidity. As the air temperature increases, the air is able to hold more water molecules. A high relative humidity means the air cannot absorb your sweat since it is already saturated with moisture. Thus, when there is a lot of moisture in the air, high temperature feels even hotter.
On the other hand, cold air is able to hold less water molecules. In consequence, low humidity levels will make a cold winter day feel even colder.
What does a dehumidifier do?
The primary function of dehumidifiers is to reduce indoor humidity levels. Different types of dehumidifiers accomplish this through different methods. Depending on the climate and location, running a dehumidifier also has some secondary benefits to the room and its occupants.
Decreased humidity level makes the environment inhospitable for mold, mildew, dust mites, and other airborne allergens. This reduces the risks of health problems in individuals and prevents damaging effects on properties.
Additionally, dehumidifiers work to eliminate unpleasant odors and improve the air quality. Less humidity in the air also helps dry laundry, preserve stored food, protect electronic equipment, and save important documents. Dehumidifiers are also useful for many commercial applications.
How does a dehumidifier work?
A dehumidifier reduces the amount of moisture in the air using different technologies.
Refrigeration
What most people are familiar with is the compressor-based dehumidifier. It works similarly to a refrigerator. This type of dehumidifier uses a compressor to power the condenser and evaporator coils that remove moisture and warm the air, respectively.
A fan draws the humid air into the machine and passes it over the cold coils. As the air temperature decreases, it loses its ability to hold moisture. It condenses into water and drips down into the internal tank or out through the drain hose.
The dryer air is then reheated and exhausted into the room at a temperature about 2°C or 4°F higher. It shouldn’t be too hot though – if you find your dehumidifier is blowing hot air, check out our troubleshooting guide. Due to this process, a compressor dehumidifier generally performs well in warmer climates. Most consumer grade models start to decline in performance at around 59°F and stop working at 41°F.
Since most houses are heated to above 60°F for human health and comfort, home dehumidifiers often use this technology. However, if you have a special application where you need to dehumidify a space with lower temperatures, there are special low temperature dehumidifiers to help with this.
Keep in mind that although a dehumidifier doesn’t cool a room there are a couple of things that can make the air feel cooler. First, is the fact that air is blowing out of the dehumidifier – when it blows across your skin it may feel cool even if the air is technically warmer than the rest of the room. Second, if the dehumidifier coils are freezing. This can happen with refrigerant dehumidifiers especially when the temperature is lower. It makes the dehumidification less effective and prior to defrosting the coils it can feel like the dehumidifier is blowing cold air. You can learn more in the linked article.
Peltier Effect
Another method that portable dehumidifiers use is called the Peltier effect or thermoelectric cooling. It is based on the idea that a voltage of electricity creates a temperature difference between the two sides of a Peltier module.
It works almost similarly to a refrigerant dehumidifier. Humid air is drawn by a small fan through the cold side of the unit. Because of this temperature difference, the moisture condenses into water and the now cold and dry air then passes through the hot side. Warmer, dryer air then exits through this side.
SInce it also needs to cool the air in order to extract the water vapor, a Peltier dehumidifier operates in the optimal range between 59°F and 89°F. It usually has a very low capacity and area of coverage, and consequently, low energy consumption. Although, it is much lighter and quieter than a refrigerant dehumidifier since it doesn’t use a compressor.
Desiccant
The other type of dehumidifier is called a desiccant. It uses a hygroscopic chemical or desiccant that absorbs or adsorbs moisture from the air. It comes in a variety of sizes, from disposable packets or tubs, to high-capacity commercial desiccant dehumidifiers.
The main difference from compressor-based dehumidifiers is the desiccant dehumidifier doesn’t cool the air to remove the moisture. Instead, moisture is transferred to the desiccant material. Wireless models use this technology to remove moisture. When they are saturated, you need to plug the unit in order to dry and renew the desiccant. Meanwhile, full-size models use a desiccant wheel filled with silica gel.
Moist air is drawn into the dehumidifier and runs through the process zone of the desiccant wheel. Moisture clings to the desiccant and separates from the air molecules. A heater warms the circulated air before it passes through the remaining part of the desiccant wheel. Moisture is then transferred from the desiccant to the warm air, effectively renewing the desiccant so that it can absorb moisture again.
Benefits of Using a Dehumidifier
Reduces allergies
Excess humidity encourages mold and mildew growth. Touching mold or inhaling mold spores may cause allergic reactions such as sneezing, runny nose, eye and skin irritations. It can also lead to allergy-induced asthma attacks and other respiratory conditions.
Dust mites are among the most common allergy and asthma triggers at home. They thrive in humid conditions and trigger allergy symptoms similar to hay fever. They cannot survive when relative humidity drops to 50 percent or below.
Helps your air conditioner
During hot and humid summer days, your air conditioning unit may not be enough to keep the indoor environment comfortable. An air conditioner lowers the temperature, and in turn, helps reduce the humidity. However, cooling down heavily moist air makes the job a lot tougher for your air conditioner, which will equate to higher air conditioning bills. Plus, running an air conditioner alone may not be able to remove all the excess moisture without running longer and making your house colder than you want.
Improves indoor air quality
High humidity levels decrease indoor comfort. You are also at higher risk of dehydration in humid conditions. The more humidity in the air the more it becomes difficult to breathe. This is because the air contains high amounts of water vapor and lower oxygen molecules. Using a dehumidifier keeps out excess moisture and odors, greatly improving indoor air quality for your health and comfort.
Preserves furniture and structures
Dry air lowers the chances of mold and mildew growth. It preserves the structural integrity of your house or other property as well as the furniture and equipment. Maintaining the humidity level within optimal range helps prevent rapid destruction caused by condensation, rust, corrosion, or pest infestation.
Summary
Running a dehumidifier does not actually make a room cooler. In fact, the air it exhausts is a few degrees warmer than the intake. But we still feel cooler because of the changes in relative humidity. A higher relative humidity means the air is more saturated with moisture. This makes the heat feel even hotter because our sweat cannot evaporate as easily.
Aside from controlling the humidity levels, a dehumidifier can benefit the user in many other ways. Maintaining optimal relative humidity ensures your health and comfort and protects your belongings from the harmful effects of excessive moisture. A dehumidifier does all of this while also helping you save money on air conditioning.
